303 Fabric Guard. Once you have 303 on the top you will find that you need to wash far less often. 3-1/2 years later water still beads on my top and it still looks brand new.
https://www.walmart.com/ip/303-Fabri...SellerId=10130
Get a mini paint roller and roll it on.
https://www.walmart.com/ip/Shur-Line...iece/854981962
Don't spray it, or it will be a huge mess all over the windows and paint. One 16oz bottle will do 2 coats.
For prep and maintenance afterward, buy a lint roller as well to remove the dust and light debris.
https://www.walmart.com/ip/Scotch-Br...dule=top_picks
303 is like clear coat and you don't want to be sealing in the dust. Have a low lint cheapo microfiber cloth handy to clean up drips before they dry.